A method for synthesizing nanometer-sized iron silicate by hydrothermal method

Abstract

This invention provides a method for synthesizing nano-sized iron silicate using a hydrothermal method. Using Fe(NO3)3·9H2O and Na2SiO3·5H2O as iron and silicon sources, respectively, this invention prepares high-purity, well-crystalled, and small-particle-size nano-iron silicate via hydrothermal synthesis. Under optimal reaction conditions of Fe / Si = 2 / 1, pH = 8, sodium dodecyl sulfate concentration = 0.7 g / L, reaction temperature = 180℃, and reaction time = 12 h, the prepared nano-iron silicate has the smallest particle size, 95.7 ± 35.0 nm. The synthesis conditions for this nano-iron silicate are relatively mild, highly controllable, and environmentally friendly. The smaller the particle size of the nano-iron silicate in the first wall material, the more adsorption sites for helium bubbles, which more effectively prevents the rupture of the first wall material caused by the aggregation of helium bubbles at grain boundaries, thereby extending the lifespan of the first wall material.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a hydrothermal method for preparing nano-iron silicate. Background Technology

[0002] Controlled nuclear fusion is a solution to today's energy problems. Compared with fossil fuels and other clean energy sources, fusion energy has advantages such as no environmental pollution and near-infinite resources. However, during the operation of a fusion reactor, the first wall material is subjected to high-energy helium ion irradiation for a long time, and the resulting large number of helium bubbles adversely affect the performance and lifespan of the first wall material. Incorporating nano-oxides into the first wall material can reduce the accumulation of helium bubbles and extend the lifespan of the first wall material (Haowei Xu, So Yeon Kim, Di Chen, Jean-Phillippe Monchoux, Thomas Voisin, Cheng Sun, Ju Li, Materials Genomics Search for Possible Helium-Absorbing Nano-Phasesin Fusion Structural Materials. Advanced Science 2022, 9, 2203555; So Yeon Kim, Sina Kavak, Kübra Gürcan Bayrak, Cheng Sun, Haowei Xu, Myeong Jun Lee, Di Chen, Yong Zhang, Emre Duygu Erhan Ayas, Eun Soo Park, Ju Li, Demonstration of Helide formation for fusion structural materials as naturallattice sinks for helium, Acta Materialia 2024, 266, 119654).

[0003] Nano-ferric silicate is an inorganic non-metallic material that can be used as a nano-oxide to extend the service life of first-wall materials. Common methods for synthesizing nano-ferric silicate include chemical precipitation and sol-gel methods. However, the particle size of nano-ferric silicate prepared by existing methods is generally between 150-300 nm (Jiang Yangfang, A method for preparing ferric silicate, CN112938998A; Tang Chunjuan, Su Jianfeng, Wang Changqing, Sun Ruirui, A carbon@ferric silicate hollow structure composite and its preparation method, CN108232167A). Furthermore, the above methods face significant challenges in terms of precise control of morphology and size, and size uniformity.

[0004] There are several common methods for synthesizing ferrosilicon materials, including chemical precipitation and sol-gel methods. However, the ferrosilicon materials prepared by existing chemical precipitation methods have a size of around 270 nm. The smaller the particle size of ferrosilicon in the first wall material, the more adsorption sites there are, effectively preventing helium bubbles from accumulating at grain boundaries, thus effectively preventing the formation of helium bubbles at the grain boundaries. Therefore, the first wall material will not be torn apart by helium bubbles to form openings, further extending the lifespan of the first wall material. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing nano-sized iron silicate using a hydrothermal method. This method offers relatively mild conditions, high controllability, and environmental friendliness, resulting in iron silicate with high purity, good crystal structure, and small particle size. Using Fe(NO3)3·9H2O and Na2SiO3·5H2O as iron and silicon sources, respectively, this invention optimizes the hydrothermal reaction conditions, such as the Fe / Si ratio, reaction time, and surfactant type. Under the following conditions—Fe / Si = 2 / 1, pH = 8, sodium dodecyl sulfate concentration of 0.7 g / L, reaction temperature of 180℃, and reaction time of 12 h—the prepared nano-sized iron silicate has the smallest particle size, 95.7 ± 35.0 nm. Smaller particle size of the nano-sized iron silicate in the first wall material provides more sites for helium bubble adsorption, effectively preventing the first wall material from cracking due to helium bubble aggregation at grain boundaries, thereby extending the lifespan of the first wall material.

[0006] To solve the technical problem of this invention, the proposed technical solution is as follows: A method for synthesizing nano-ferric silicate by hydrothermal method, comprising the following steps:

[0007] (1) Prepare the solution: Measure deionized water into a beaker, add an appropriate amount of Fe(NO3)3·9H2O to prepare Fe(NO3)3·9H2O solution; then measure deionized water into a beaker, add an appropriate amount of Na2SiO3·5H2O to prepare Na2SiO3·5H2O solution.

[0008] (2) Hydrothermal reaction: The Fe(NO3)3·9H2O solution and Na2SiO3·5H2O solution from step (1) were added to a beaker, with a molar ratio of Fe(NO3)3·9H2O to Na2SiO3·5H2O of 2:1; the mixture was stirred evenly with a magnetic stirrer; then sodium dodecyl sulfate surfactant was added with a concentration of 0.7 g / L; ammonia was added to adjust the pH of the mixture to 8, and after stirring evenly, the mixture was transferred to a polytetrafluoroethylene liner, and a sealed hydrothermal reactor was assembled to carry out the hydrothermal reaction.

[0009] (3) Washing, drying and grinding: After the reaction is completed, the solid is washed, dried and then ground to obtain nano-iron silicate particles.

[0010] Preferably, in step (2), the Na2SiO3·5H2O aqueous solution is slowly poured into the Fe(NO3)3·9H2O aqueous solution and stirred at 1000 rpm for 10 min; then 42 mg of sodium dodecyl sulfate is added and stirred at 1000 rpm for 10 min; finally, the pH is adjusted to 8 with ammonia.

[0011] Preferably, the reaction temperature of the hydrothermal reaction in step (2) is 180°C and the reaction time is 12h; after the reaction is completed, the hydrothermal reactor is taken out and cooled to room temperature.

[0012] Preferably, in step (3), after the collected iron silicate slurry is filtered, it is washed with deionized water until the pH is 7, and then the solid is dried in an oven at 80°C for 12 hours. After the drying is completed, it is sealed and stored.

[0013] Preferably, (1) Measure 30 mL of deionized water into a beaker, and then take an appropriate amount of Fe(NO3)3·9H2O to prepare solution I; measure 30 mL of deionized water into a beaker, and take an appropriate amount of Na2SiO3·5H2O to prepare solution II; stir at 1000 rpm for 20 min respectively; slowly pour solution II into solution I, and stir at 1000 rpm for 10 min; then add 0.7 g / L sodium dodecyl sulfate, and stir at 1000 rpm for 10 min; adjust the pH to 8 with ammonia water;

[0014] (2) Pour the reaction solution into a hydrothermal reactor and carry out the hydrothermal reaction at a temperature of 180℃ for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0015] (3) Filter the iron silicate slurry collected in step (2) and wash it with deionized water until the pH is 7. Place the solid obtained after filtration in a petri dish, put it in an oven at 80°C and dry it for 12 hours. After grinding, seal and store it.

[0016] Preferably, (1) 30 mL of deionized water is placed in a beaker, 2 mmol of Fe(NO3)3·9H2O is added, and the mixture is stirred at 1000 rpm for 20 min to prepare Fe(NO3)3·9H2O solution; then 30 mL of deionized water is placed in a beaker, 1 mmol of Na2SiO3·5H2O is added, and the mixture is stirred at 1000 rpm for 20 min to prepare Na2SiO3·5H2O solution; the Na2SiO3·5H2O solution is slowly poured into the Fe(NO3)3·9H2O solution, and the mixture is stirred at 1000 rpm for 10 min; then 42 mg of sodium dodecyl sulfate 0.7 g / L is added, and the mixture is stirred at 1000 rpm for 10 min; then the pH is adjusted to 8 with ammonia water.

[0017] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is completed, remove the hydrothermal reactor and cool it to room temperature.

[0018] (3) After filtering the iron silicate slurry collected in step (2), wash it with deionized water until the pH is 7. Then the solid is dried in an oven at 80°C for 12 hours, ground and sealed for storage. The particle size of the prepared iron silicate is 95.7±35.0nm.

[0019] Beneficial effects of the present invention

[0020] This invention provides a hydrothermal preparation method for nano-ferric silicate. The hydrothermal reaction is carried out in a relatively closed system, which avoids the introduction of external impurities, resulting in a product with high purity and small nano-ferric silicate particle size.

[0021] This invention screened different Fe / Si ratios, reaction times, reaction temperatures, and surfactant concentrations and types. It was determined that the smallest particle size of the prepared nano-ferric silicate was achieved at the following conditions: Fe / Si = 2 / 1, pH = 8, sodium dodecyl sulfate concentration = 0.7 g / L, reaction temperature = 180 °C, and reaction time = 12 h. The nano-ferric silicate prepared in Example 1 had the smallest particle size, 95.7 ± 35.0 nm.

[0022] Application of the nano-iron silicate prepared by this invention: In the first wall material of a nuclear fusion device, the addition of nano-iron silicate can reduce the aggregation of helium bubbles at the grain boundaries of the first wall material and extend the service life of the first wall material.

[0023] The smaller the particle size of nano-iron silicate, the more dispersed it is after being incorporated into the first wall material, and the more sites it has for adsorbing helium bubbles. This can more effectively prevent the first wall material from cracking due to the aggregation of helium bubbles at the grain boundaries, thereby extending the service life of the first wall material.

[0024] Compared with traditional chemical precipitation methods, the hydrothermal method offers significant advantages in terms of precise morphology control, size uniformity, crystallinity, purity, and multi-component composite capabilities of nanomaterials. These advantages make it an ideal method for large-scale, reproducible preparation of small-particle-size ferric silicate nanoparticles. The nanoparticles prepared by this method not only have controllable particle size but also exhibit high size uniformity, good dispersibility, and minimal agglomeration. Benefiting from the high-temperature, high-pressure reaction environment's promoting effect on crystal growth, the hydrothermal method can directly generate highly crystalline nanomaterials without the need for additional calcination processes. Attached Figure Description

[0025] Figure 1 XRD patterns of Examples 1-3

[0026] Where a: Example 1; b: Example 2; c: Example 3

[0027] Figure 2 TEM images and particle size distribution diagrams of Comparative Examples 1-8

[0028] Figure 3 TEM images and particle size distribution diagrams of Comparative Examples 1-7

[0029] Figure 4 TEM image and particle size distribution map of Example 1

[0030] Figure 5 TEM images and particle size distribution diagrams of Comparative Examples 1-9 Detailed Implementation

[0031] Example 1

[0032] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecyl sulfate (0.7 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0033] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0034] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =2:1)-0.7.

[0035] Example 2

[0036] (1) Measure 30 mL of deionized water into a beaker, add 1 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecyl sulfate (0.7 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0037] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0038] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =1:1)-0.7.

[0039] Example 3

[0040] (1) Measure 30 mL of deionized water into a beaker, add 1 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 2 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecyl sulfate (0.7 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0041] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0042] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =1:2)-0.7.

[0043] Comparative Example 1-1

[0044] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 30 mg of sodium dodecyl sulfate (0.5 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0045] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0046] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =2:1)-0.5.

[0047] Comparative Examples 1-2

[0048] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 54 mg of sodium dodecyl sulfate (0.9 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0049] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0050] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =2:1)-0.9.

[0051] Comparative Examples 1-3

[0052] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecyl sulfate (0.7 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0053] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 160°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0054] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =2:1)-160.

[0055] Comparative Examples 1-4

[0056] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecyl sulfate (0.7 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0057] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 200°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0058] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =2:1)-200.

[0059] Comparative Examples 1-5

[0060] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecyl sulfate (0.7 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0061] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 8 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0062] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =2:1)-8.

[0063] Comparative Examples 1-6

[0064] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecyl sulfate (0.7 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0065] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 16 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0066] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =2:1)-16.

[0067] Comparative Examples 1-7

[0068] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecylbenzenesulfonate (0.7 g / L), and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia.

[0069] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0070] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :n Si =2:1)-12 SDBS .

[0071] Comparative Examples 1-8

[0072] (1) Measure 30 mL of deionized water into a beaker, add 2 mmol of Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare a Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol of Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare a Na2SiO3·5H2O solution. Slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 20 min; then adjust the pH to 8 with ammonia.

[0073] (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is complete, remove the hydrothermal reactor and cool it to room temperature.

[0074] (3) After filtering the ferric silicate slurry collected in step (2), wash it with deionized water until the pH reaches 7. Then, dry the solid in an oven at 80°C for 12 hours, grind it, and seal it for storage. Name it Iron silicate / (n Fe :nSi =2:1)-12-0.

[0075] Comparative Examples 1-9

[0076] The preparation of ferric silicate by chemical precipitation method is as follows:

[0077] (1) Weigh out a certain amount of Fe(NO3)3·9H2O and Na2SiO3·9H2O respectively, dissolve them in a certain volume of deionized water to prepare solutions, and place them on a magnetic stirrer and stir for a certain time.

[0078] (2) Add Na2SiO3 stock solution to Fe(NO3)3 stock solution at a molar ratio of Fe / Si = 2 / 1 and stir for a certain period of time;

[0079] (3) Slowly add ammonia water to the above mixed solution and stir to adjust the pH value to 11, then activate it at 60℃ for 12h;

[0080] (4) Filter out the activated precipitate, rinse repeatedly with deionized water until the pH of the filtrate is stable, then dry in an oven at 80°C for 12 hours, grind and seal for storage.

[0081] Physical performance testing

[0082] The nano-sized iron silicate prepared in Examples 1, 2, and 3 were characterized by X-ray diffraction, and the results are as follows: Figure 1 As shown, the prepared nano-iron silicate is an amorphous material.

[0083] Examples 1-3 prepared ferrosilicon with different iron-silicon ratios. In Example 1, the ferrosilicon had the smallest particle size when Fe / Si = 2 / 1 (Table 1). Comparative Examples 1-1, 1-2, and Example 1 compared the effect of sodium dodecyl sulfate concentration on the particle size of nano-ferrosilicon; the optimal concentration was 0.7 g / L. Comparative Examples 1-3, 1-4, 1-5, and 1-6 compared the effects of reaction temperature and reaction time on the particle size of nano-ferrosilicon. Comparative Examples 1-7, 1-8, and 1-9 compared the effects of other surfactants (sodium dodecylbenzenesulfonate), no surfactant, and other preparation methods on the particle size of nano-ferrosilicon. The ferrosilicon particles prepared under these conditions were larger than those prepared using the hydrothermal method and with sodium dodecyl sulfate as a surfactant.

[0084] The nano-sized iron silicates prepared in Comparative Examples 1-8, 1-7, Example 1, and 1-9 were characterized by transmission electron microscopy (TEM), and the results are as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, in Example 1, the molar ratio of Fe(NO3)3·9H2O and Na2SiO3·5H2O was 2:1, the concentration of sodium dodecyl sulfate was 0.7 g / L, the reaction time was 12 h, and the reaction temperature was 180 °C. Under these conditions, the nano-iron silicate particles had the smallest size.

[0085] Application of the nano-iron silicate prepared by this invention: In the first wall material of a nuclear fusion device, the addition of nano-iron silicate can reduce the aggregation of helium bubbles at the grain boundaries of the first wall material and extend the service life of the first wall material.

[0086] The smaller the particle size of nano-iron silicate, the more dispersed it is after being incorporated into the first wall material, and the more sites it has for adsorbing helium bubbles. This can more effectively prevent the first wall material from cracking due to the aggregation of helium bubbles at the grain boundaries, thereby extending the service life of the first wall material.

[0087] Table 1. Particle size distribution of iron silicate prepared in the examples and comparative examples.

[0088] Ferric silicate Particle size distribution (nm) Example 1 95.7±35.0 Example 2 191.9±51.9 Example 3 171.4±53.5 Comparative Example 1-1 120.4±34.9 Comparative Examples 1-2 104.8±28.6 Comparative Examples 1-3 141.5±44.9 Comparative Examples 1-4 115.0±45.5 Comparative Examples 1-5 179.7±61.8 Comparative Examples 1-6 277.9±47.7 Comparative Examples 1-7 134.1±57.9 Comparative Examples 1-8 159.4±50.2 Comparative Examples 1-9 276.6±82.2

[0089] As can be seen from the above embodiments, the present invention successfully prepared nano-iron silicate based on the hydrothermal method. By optimizing the Fe / Si ratio, reaction time, reaction temperature and surfactant concentration, nano-iron silicate particles with smaller particle size were obtained.

[0090] This invention is not limited to the specific technical solutions described in the above embodiments. All technical solutions formed by equivalent substitutions are within the scope of protection claimed by this invention.

Claims

1. A method for hydrothermal synthesis of nano-ferric silicate, characterized in that: (1) Measure 30 mL of deionized water into a beaker, add 2 mmol Fe(NO3)3·9H2O, and stir at 1000 rpm for 20 min to prepare Fe(NO3)3·9H2O solution; then measure 30 mL of deionized water into a beaker, add 1 mmol Na2SiO3·5H2O, and stir at 1000 rpm for 20 min to prepare Na2SiO3·5H2O solution; slowly pour the Na2SiO3·5H2O solution into the Fe(NO3)3·9H2O solution, and stir at 1000 rpm for 10 min; then add 42 mg of sodium dodecyl sulfate 0.7 g / L, and stir at 1000 rpm for 10 min; then adjust the pH to 8 with ammonia water. (2) Pour the mixed solution from step (1) into a hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 180°C for 12 hours. After the reaction is completed, remove the hydrothermal reactor and cool it to room temperature. (3) After filtering the iron silicate slurry collected in step (2), wash it with deionized water until the pH is 7. Then dry the solid in an oven at 80°C for 12 h, grind it and seal it for storage. The particle size of the prepared iron silicate is 95.7±35.0 nm.

2. The method for hydrothermal synthesis of nano-ferric silicate according to claim 1, characterized in that: The prepared nano-iron silicate is an amorphous material.

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